Apparatus for preheating fine granular material

ABSTRACT

A plurality of eddy chambers of the cyclone separator type are arranged in superimposed levels through which the material passes downward in series and through which the hot gases travel upward in series. Each eddy chamber is provided with a duct for discharging material separated in the chamber. The material discharge duct of each eddy chamber in at least the uppermost level is provided with a shutoff valve, and the material discharge duct of each eddy chamber in at least the lowermost level is constructed without any shutoff valve.

United States Patent Polysius et al.

[54] APPARATUS FOR PREHEATING FINE GRANULAR MATERIAL [72] inventors: Jochen Polysius; Horst Ritzmann, both of Neubeckum, Germany [73] Assignee: Polyslus AG, Neubeckum, Germany [22] Filed: May 28, 1970 [21] Appl. No: 41,199

[30] Foreign Application Priority Data Aug. 12, i969 Germany ..P 19 41 045.8

[52] U.S. Cl. ..263/21 A, 34/57 R 511 ,,F27b 15/00 [58] Field or Search ..263/21 R, 21 A; 34/57 R, 57 A [56] References Cited UNITED STATES PATENTS 2,802,280 8/1957 Sylvest ..34/57 R 3,419,968 1/1969 Jager ..34/57 R FOREIGN PATENTS 0R APPLICATIONS 441,125 l/l968 Switzerland ..263/21 A 747,586 4/1956 Great Britain. ..54/57 R 1,154,768 9/1963 Germany ......34/s7 R Primary Examiner-Charles J. Myhre I Attorney-Marshall & Yeasting [5 7] ABSTRACT A plurality of eddy chambers of the cyclone separator type are arranged in superimposed levels through which the material passes downward in series and through which the hot gases travel upward in series. Each eddy chamber is provided with a duct for discharging material separated in the chamber. The material discharge duct of each eddy chamber in at least the uppermost level is provided with a shutoff valve, and the material discharge duct of each eddy chamber in at least the lowermost level is constructed without any shutoff valve.

7 Claims, 1 Drawing Figure APPARATUS FOR PREHEATING FINE GRANULAR MATERIAL BACKGROUND or THE INVENTION The invention relates to an apparatus forthe preheating of fine granular material by means of hot gases. consisting of a plurality of eddy chambers of the cyclone type arranged at several superimposed levels, wherein the hot gas stream which is distributed to the eddy chambers of the first, lowermost stage is reunited in a central eddy chamber of the second stage, before it is again distributed to-the eddy chambers of the third stage, while the dividedstream of material coming from the eddy chambers of the third stage is united in the central eddy chamber of the second stage, before it is again distributed to the eddy chambers of the first stage.

In the previously known preheaters of the type which has been described, the material discharge ducts of 'all of the cyclone-type eddy chambers are provided with adjustable shutoff devices, for example balanced dampers. Their purpose consists, on the one hand, in hindering the passage of gas through the material discharge ducts, and on the other hand in making possible nevertheless the passage of the material. These known devices, however, are'subject to various disadvantages.

Since the shutoff devices in the material discharge-ducts come into contact with gas and material at a high temperature, particularly in the lower stages of the preheater, they are subject to a severe thermal and mechanical deterioration, which often leads to jamming at the shutofi' devices, which occasionally, as with a stopping of the material discharge duct in question, leads to a severe impairment of the operation.

SUMMARY OF THE INVENTION The invention accordingly has for its object to design an apparatus of the class hereinbefore described in such a manner that the difficulties are eliminated.

In accordance with the invention this object is achieved by providing the material discharge ducts of the eddy chambers with shutoff devices in at least one stage; and by constructing According: to a preferredembodimentof the invention, the

, open cross section of the material discharge ducts which are constructed without shutoff devices is advantageously made at least great enough so that a maximum of 80 percent, preferably a maximum of 50 percent of the cross, section is occupied by material, and at the most greatenough so that in total a maximum of 10 percent, preferably a maximum of 5 percent of the entire gas stream passes through the material discharge ducts of this stage.

In accordance with a further advantageous feature of the invention, in at least one stage the cyclone-type eddy chambers are provided with dip pipes, and in at least one stage in the zone of higher gas temperature, the eddy chambers are constructed without dip pipes.

The dip pipes, like the shutofi devices, are among those elements of thecyclone-type eddy chambers which are subject to severe thermal and mechanical deterioration, particularly in the lower zone of the preheater. The omission of the dip pipes in the preheater stage of higher temperature thus promotes the reliability and freedomfrom maintenance of the installation. The retention of the dip pipes in at least one preheater stage lying in the zone of lower temperature, on the other hand, guarantees the necessary good separation, and in particular the perfect removal of dust from the gas stream leaving the preheater.

the material discharge ductsof the eddy chambers without 1 shutoff devices in atleast one stage lying in a zone of higher gas temperature.

In the research which was the basis of the present invention, it was surprisingly discovered that in the zone of high gas temperature the shutoff devices which are susceptible to rapid deterioration in the material discharge passages can be dispensed with, without impairment of the general operating efficiency of the installation, if the material discharge ducts of the cyclone-type eddy chambers only in at least one of the subsequent stages which lie in a zone of lower gas temperature are provided with shutoff devices, in the usual manner. The omission of the shutoff devices in the critical high temperature stages of the preheater eliminates the source of the difficulty which has been described, and thereby substantially diminishes the maintenance required by the installation and remarkably increases its reliability. The omission of the shutoff devices in the material discharge ducts of one stage of the preheater impairs only insignificantly the separation of the material in the eddy chambers of this stage; in some cases a somewhat prolonged dwell time of the material in the eddy chambers of this stage may even be conducive to the attainment of an intensive heat exchange. On the other hand, the retention of shutoff devices in the material discharge ducts of at least one subsequent stage lying in a zone of lower temperature guarantees the necessary perfect separation of the material from the gas stream, so that no additional ,dust removing capacity is required for the gas stream emerging from the preheater. v

The present invention thus combines 'the advantages of a high reliability attained by the omission of certain specific elements which are troublesome and subject to deterioration, and a good-heat exchange efficiency with small dust removing capacity.

BRIEF DESCRIPTION OF THE DRAWING Thedrawing is a schematic longitudinal section of a preferred form of apparatus embodying the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated apparatus serves for the preheating of fine separators, and are referred to hereinafter as cyclone separators for the sake of simplicity. The lowermost stage of the preheater consists of the cyclone separators 2, 2', the second stage consists of one central cyclone separator 3, the third stage consists of two cyclone separators 4. 4"and the fourth stage consists of two cyclone separators 5, 5'. V

These cyclone separators are connectedby means of their gas and material ducts as follows: the gas duct 6 coming from the rotary kiln 1 is divided and leads to both of the cyclone separators 2 and 2'. Their gas discharge ducts 7. 7' both discharge into the'central cyclone separator 3, and preferably are tangential in the same sense of rotation. The gas discharge duct 8 of the cyclone separator 3 is divided and leads to the cyclone separators 4 and 4', which are connected by means of their gas discharge pipes 9, 9 with the cyclone separators 5, 5. The gas discharge ducts 10, 10' of the latter cyclone separators are connected to a common blower 11.

The material discharge ducts 12, 12' of the cyclone separators 5, 5 discharge into the gas duct 8. The material discharge ducts 13, 13' of the cyclone separators-4, 4 are connected to the gas ducts 7, 7', while the material discharge 14 of the cyclone separator 3 discharges into the upper end of the gas duct 6. The materialdischarge ducts 15, 15 of the two lowermost cyclone separators are directly connected with the rotary kiln 1 or with its inlet housing.

While the material discharge ducts 12, 12' and 13, 13' of the two uppermost stages of the preheater are provided with shutoff devices 120, l2'a, 13a, 13a, for example in the form of balanced dampers, such devicesare lacking in the material discharge ducts 14, 15 and 15 of the two lower preheater stages. Both cyclone separators 2, 2' of the lowermost preheater stages'furthermore are constructed without dip pipes, while all of the other cyclone separators 3,4, 4,-5, 5' are provided with the usual dip pipes 3a, 4a, 4'a, 5a, and S'a.

The path of flow of the hot gasescoming from the rotary kiln 1 is indicated by arrows 17; the hot gas stream is distributed first to the two cyclone separators 2,2, is then reunited in the central cyclone separator 3, is distributed anew to the cyclone separators 4, 4 then passes through the cyclone separators 5, 5 and is finally withdrawn through the blower 11.

The countercurrent path of the material being preheated is marked by the arrows 18: the material entering the gas ducts 9, 9 is separated in the cyclone separators 5, 5, then travels into the gas duct 8, is led to the cyclone separators 4, 4, travels after separation in these cyclone separators into the gas ducts 7, 7, is brought together anew in the central cyclone separator 3 and is once more distributed, after entering the gas duct 6, to the two cyclone separators 2, 2, before it travels, highly preheated, into the rotary kiln 1.

We claim:

1. Apparatus for preheating fine granular material by means of hot gases, comprising a plurality of eddy chambers of the cyclone separator type, arranged in superimposed levels through which the material passes downward in series and through which the hot gases travel upward in series, each eddy chamber being provided with a bottom discharge duct for discharging material separated in the chamber, the discharge duct of each eddy chamber in at least the uppermost level being provided with means for shutting off the flow of material through the duct, and the discharge duct of each eddy chamber in at least the lowermost level being constructed without any means for shutting off the flow of material through the duct, and being constantly open for simultaneous downward flow of material and upward flow of a portion of the hot gases entering the eddy chamber.

2. Apparatus according to claim 1 wherein the eddy chambers are arranged in at least three superimposed levels, the material discharge duct of each eddy chamber in the two lowermost levels being constructed without any shutoff means and the material discharge duct of each of the other eddy chambers being provided with a shutoff means.

3. Apparatus according to claim 1 wherein the open cross section of each material discharge duct that is constructed without a shutoff means is at least great enough so that not more than of the cross section is occupied by the material flowing therethrough, and is at least small enough so that more than 10 percent of the gas entering the corresponding eddy chamber passes through such material discharge duct.

4. Apparatus according to claim 1 wherein each eddy chamber in at least the lowermost level is constructed without a dip pipe, and each eddy chamber in at least the uppermost level is provided with a dip pipe.

5. Apparatus according to claim 4 wherein each eddy chamber whose material discharge duct is constructed without any shutoff means is constructed without a dip pipe.

6. Apparatus according to claim 1 wherein the eddy chambers are arranged in at least three superimposed levels, the first and third levels from the bottom each comprising two eddy chambers, and the second level from the bottom comprising only one eddy chamber having two gas inlet ducts, which lead from the two eddy chambers of the first level and into each of which discharges a material supply duct leading from one of the eddy chambers of the third level.

7. Apparatus according to claim 6 wherein a fourth level from the bottom comprises two eddy chambers each of which has a gas inlet duct leading from one of the eddy chambers of the third level, the latter eddy chambers being connected to a gas inlet duct, which leads from the eddy chamber of the second level and into which discharge two material supply ducts leading from the eddy chambers of the fourth level, each of such material supply ducts being provided with a shutoff valve.

* i i i 

1. Apparatus for preheating fine granular material by means of hot gases, comprising a plurality of eddy chambers of the cyclone separator type, arranged in superimposed levels through which the material passes downward in series and through which the hot gases travel upward in series, each eddy chamber being provided with a bottom discharge duct for discharging material separated in the chamber, the discharge duct of each eddy chamber in at least the uppermost level being provided with means for shutting off the flow of material through the duct, and the discharge duct of each eddy chamber in at least the lowermost level being constructed without any means for shutting off the flow of material through the duct, and being constantly open for simultaneous downward flow of material and upward flow of a portion of the hot gases entering the eddy chamber.
 2. Apparatus according to claim 1 wherein the eddy chambers are arranged in at least three superimposed levels, the material discharge duct of each eddy chamber in the two lowermost levels being constructed without any shutoff means and the material discharge duct of each of the other eddy chambers being provided with a shutoff means.
 3. Apparatus according to claim 1 wherein the open cross section of each material discharge duct that is constructed without a shutoff means is at least great enough so that not more than 80% of the cross section is occupied by the material flowing therethrough, and is at least small enough so that more than 10 percent of the gas entering the corresponding eddy chamber passes through such material discharge duct.
 4. Apparatus according to claim 1 wherein each eddy chamber in at least the lowermost level is constructed without a dip pipe, and each eddy chamber in at least the uppermost level is provided with a dip pipe.
 5. Apparatus according to claim 4 wherein each eddy chamber whose material discharge duct is constructed without any shutoff means is constructed without a dip pipe.
 6. ApparatuS according to claim 1 wherein the eddy chambers are arranged in at least three superimposed levels, the first and third levels from the bottom each comprising two eddy chambers, and the second level from the bottom comprising only one eddy chamber having two gas inlet ducts, which lead from the two eddy chambers of the first level and into each of which discharges a material supply duct leading from one of the eddy chambers of the third level.
 7. Apparatus according to claim 6 wherein a fourth level from the bottom comprises two eddy chambers each of which has a gas inlet duct leading from one of the eddy chambers of the third level, the latter eddy chambers being connected to a gas inlet duct, which leads from the eddy chamber of the second level and into which discharge two material supply ducts leading from the eddy chambers of the fourth level, each of such material supply ducts being provided with a shutoff valve. 